Wednesday, 8 January 2014

Bones, Boats, and Ice Sheets: Who were the first people in the Americas?

Ancient people can be hard to pin down. Archaeologists do about as much debating as they do digging, partly because no one wants to admit that the cool spearhead they found isn’t that important, and partly because the travel itineraries of prehistoric people can be incredibly hard to wrap you head around. 

Nowhere is this more true than in the Americas. Columbus was by no means the first European to arrive on the scene but he is generally credited as opening the can of worms that is the Archaeology of North and South America. When he made landfall in 1492 it rapidly became apparent that he hadn’t discovered anything new for humanity. People were everywhere. Millions of them. Ever since, scientists have been try to sort out where they came from. 

For most of the 20th century, the accepted wisdom was that the first people in the Americas were the Clovis people who left evidence in the form of stone tools around the New Mexico town of Clovis around 13,500 years ago. This all made good sense. Scientists had long known that around 14,000 years ago an ice-free corridor opened up in the previously impassible ice sheet that had been covering North America. The thing about ice sheets is that they take a lot of water to make and that water comes from the ocean. The upshot is that when the ice-free corridor opened up, sea levels were about 120 meters (400 feet) lower than today and Alaska was connected to Russia by what is known as the Berring Land Bridge. The Clovis people, is was said, cross the land bridge, threaded the needle of the ice-free corridor, and spawned all the first peoples of North and South America. Unfortunately, it appears that the story is too simple and comprehensible to be true. 

Doubts first began to surface in the 1970’s when two sites thousands of miles apart began to yield artifacts that were older than the Clovis culture. The first was in Pennsylvania at Meadowcroft rock shelter, where humans had apparently been making tools 2,000 years before the ice-free corridor opened up. The second site was in Chili and it revealed the remains of a tent structure dating to 14,800 years ago as well as a few tools. The problem with the Chilean site was that the tools looked nothing like those of the Clovis people. So either the Clovis people arrived sooner than we thought and abandoned their signature tools as soon as they hit South America, or there were people living in Chili while the Clovis people were still pondering the edge of an impassable Russian glacier.

Archaeologists responded to these findings in much the same way that all scientists initially respond to evidence that contradicts what they all believe. They either ignored it or made fun of it. It wasn’t until a team of respected archaeologists traveled to Chili in 1997 to validate the site that people began questioning the Clovis hypothesis

So if people didn’t walk to the Americas, how did they get here? Aside from the all-too-obvious explanation involving aliens, it would appear that they came by sea. Archaeologists have found evidence in sites dotting the Pacific coast that people were living in sea caves in Oregon and on islands off the coast of California at the same time, or slightly before Clovis people first arrived. This suggests that they used boats to travel along the coast all the way from Asia to North America. The idea isn’t as crazy as it seems, though. People made it to Australia (presumably by boat since Australia is an island) at least 45,000 years ago. Evidence suggests that the first North American could have followed a “kelp highway” along the southern edge of the glaciers and maintained much of the same diet for the entire trip. 

Still, more evidence has suggested that the same thing might have happened on the East coast of North America. There, researchers have found tools that look startlingly like those of the Solutrean culture of Western Europe. Tools dating to 22,760 years ago have been found with mastodon bones at sites in North Carolina. Even the people presenting this idea admit that the hard evidence does not yet exist to support it, but it’s worth keeping an eye on. 

The trouble with the coastal travel hypothesis is that most of the sites that would provide evidence in favour of it are now underwater. The upshot is that we are left scratching our heads. All we know for certain is that people have been in the Americas for a very long time and that the technology they used to get here is likely more advanced than we previously dared to think.